The present invention relates generally to devices and methods for treating occluded or stenoic blood vessels. More particularly, the present invention relates to devices and methods for providing temporary placement of a filter in a blood vessel during a procedure to remove an occlusion or stenosis.
Angioplasty, atherectomy and stent placement, among other procedures, have become well accepted for treatment of coronary lesions. These procedures are often performed as an alternative to coronary bypass. It is also possible, however, that a saphenous vein graft, which is used to bypass coronary lesion, may itself develop a lesion. These lesions may also be treated by minimally invasive procedures such as angioplasty, atherectomy and/or stent placement.
When lesions are treated by these minimally invasive, percutaneous methods, it is possible that particles of plaque, thrombus or other material may break loose from the lesion and drift distally into the smaller coronary arteries. When these minimally invasive methods are performed on native arteries, the plaque or thrombus released during the procedure rarely causes embolization. When these procedures are performed on saphenous vein grafts, however, the incidence of embolism due to the breaking off of plaque or thrombus from the vein graft is substantially greater than from native arteries.
The increased incidence of embolization is believed to be due, at least in part, to the larger diameter of the bypass graft relative to the native artery. The larger diameter of the graft results in a slower blood flow velocity through the graft than the native artery. In addition, the plaque and thrombus of vein grafts is somewhat more fragile than that found in native arteries.
As the difference in embolism associated with treatment of native arteries and vein grafts has been noted, it would be desirable to develop techniques to reduce embolism associated with treatment of vein graft lesions. Additionally, where stent placement or other minimally invasive treatments are performed on the carotid artery, it would be desirable to limit the drift of plaque and thrombus toward the brain.
The present invention relates generally to devices and methods for treating occluded or stenoic blood vessels. More particularly, the present invention relates to devices and methods for providing temporary placement of a filter in a blood vessel during a procedure to remove an occlusion or stenosis. A system in accordance with the present invention features an outer shaft having a proximal end, a distal end and a wall defining an outer shaft lumen. The system also includes a stop mechanism disposed within the outer shaft lumen. The stop mechanism is preferably configured such that relative axial movement between the guidewire and the outer shaft may be selectively precluded.
In certain implementations of the invention, a proximal guidewire port extends through the wall of the outer shaft for allowing the guidewire to pass through the wall so that it is partially disposed within the shaft lumen. In an advantageous embodiment, the stop mechanism is disposed distally of the proximal guidewire port.
In one aspect of the invention, the stop mechanism is adapted to mechanically engage the guidewire. In an additional aspect of the invention, the stop mechanism is adapted to frictionally engage the guidewire. In yet another aspect of the invention, the stop mechanism is adapted to apply a compressive force to the guidewire.
The stop mechanism may feature a stop member. In certain implementations, the stop member features a ring, and the stop mechanism includes a stop fixed to the guidewire. In one embodiment, the stop member defines an aperture having a inner radial extent, and the stop has an outer radial extent. In an advantageous embodiment, the stop member defines an aperture having an inner radial extent, and the stop has an outer radial extent that is generally greater than the inner radial extent of the aperture defined by the stop member.
In certain implementations of the invention, the stop member features a distal mating surface and the stop features a proximal mating surface. In an advantageous embodiment, the stop and the stop member are configured such that the proximal mating surface of the stop seats against the distal mating surface of the stop member.
In certain implementations, the system features an inner shaft slidingly disposed within the outer shaft lumen. A gripper may be operatively coupled between the inner shaft and the outer shaft. Preferably, the gripper is configured such that relative axial movement between the inner shaft and the outer shaft causes the gripper to grasp the guidewire. In certain implementations, the gripper features a collet.
In certain implementations, the gripper is fixed to the outer shaft. In other implementations, the gripper is fixed to the inner shaft.